package vip.xiaonuo.facedoor.modular.visitor.controller;

public class Event {

    private static volatile Event event;

    private Event() {

    }

    public static Event getInstance() {
        if (event == null) {
            synchronized (Event.class) {
                if (event == null) {
                    event = new Event();
                }
            }
        }
        return event;
    }
}
